scholarly journals Microbiome divergence of marine gastropod species separated by the Isthmus of Panama

2021 ◽  
Author(s):  
Alexander T Neu ◽  
Mark E Torchin ◽  
Eric E Allen ◽  
Kaustuv Roy
Keyword(s):  
Whole Body ◽  
Similarity Metrics ◽  
Gastropod Species ◽  
Shell Surface ◽  
Marine Gastropods ◽  
Microbiome Composition ◽  
Isthmus Of Panama ◽  
Surface Samples ◽  
Species Pairs ◽  
Specific Manner

The rise of the Isthmus of Panama ~3.5 mya separated populations of many marine organisms, which then diverged into new geminate sister species currently living in the Eastern Pacific Ocean and Caribbean Sea. However, we know very little about how such evolutionary divergences of host species have shaped their microbiomes. Here, we compared the microbiomes of whole-body and shell-surface samples of geminate species of marine gastropods in the genera Cerithium and Cerithideopsis to those of congeneric outgroups. Our results show that the effects of the Isthmus on microbiome composition varied among host genera and between sample types within the same hosts. In the whole-body samples, microbiome compositions of geminate species pairs in the focal genera tended to be similar, likely due to host filtering, although the strength of this relationship varied among the two groups and across similarity metrics. Shell-surface communities show contrasting patterns, with co-divergence between the host taxa and a small number of microbial clades evident in Cerithideopsis, but not Cerithium. These results suggest that (i) the rise of the Isthmus of Panama affected microbiomes of geminate hosts in a complex and clade-specific manner and (ii) host-associated microbial taxa respond differently to vicariance events than the hosts themselves.

scholarly journals Evaluating the role of contracting and expanding rainforest in initiating cycles of speciation across the Isthmus of Panama

2012 ◽  
Vol 279 (1742) ◽  
pp. 3520-3526 ◽  
Author(s):  
Brian Tilston Smith ◽  
Amei Amei ◽  
John Klicka
Keyword(s):  
Bird Species ◽  
Tropical Regions ◽  
Isthmus Of Panama ◽  
Species Pairs ◽  
The Matrix ◽  
High Species Richness ◽  
The Rich ◽  
The Tropics ◽  
The Impact

Climatic and geological changes across time are presumed to have shaped the rich biodiversity of tropical regions. However, the impact climatic drying and subsequent tropical rainforest contraction had on speciation has been controversial because of inconsistent palaeoecological and genetic data. Despite the strong interest in examining the role of climatic change on speciation in the Neotropics there has been few comparative studies, particularly, those that include non-rainforest taxa. We used bird species that inhabit humid or dry habitats that dispersed across the Panamanian Isthmus to characterize temporal and spatial patterns of speciation across this barrier. Here, we show that these two assemblages of birds exhibit temporally different speciation time patterns that supports multiple cycles of speciation. Evidence for these cycles is further corroborated by the finding that both assemblages consist of ‘young’ and ‘old’ species, despite dry habitat species pairs being geographically more distant than pairs of humid habitat species. The matrix of humid and dry habitats in the tropics not only allows for the maintenance of high species richness, but additionally this study suggests that these environments may have promoted speciation. We conclude that differentially expanding and contracting distributions of dry and humid habitats was probably an important contributor to speciation in the tropics.

Postural Preparation to Making a Step: Is There a “Motor Program” for Postural Preparation?

2007 ◽  
Vol 23 (4) ◽  
pp. 261-274 ◽  
Author(s):  
Adriana M. Degani ◽  
Alessander Danna-Dos-Santos ◽  
Mark L. Latash
Keyword(s):  
Reaction Time ◽  
Simple Reaction Time ◽  
Center Of Pressure ◽  
Motor Program ◽  
Whole Body ◽  
Single Motor ◽  
Simple Reaction ◽  
Specific Manner ◽  
Young Subjects ◽  
Straight Ahead

We tested the hypothesis that a sequence of mechanical events occurs preceding a step that scales in time and magnitude as a whole in a task-specific manner, and is a reflection of a “motor program.” Young subjects made a step under three speed instructions and four tasks: stepping straight ahead, down a stair, up a stair, and over an obstacle. Larger center-of-pressure (COP) and force adjustments in the anteriorposterior direction and smaller COP and force adjustments in the mediolateral direction were seen during stepping forward and down a stair, as compared with the tasks of stepping up a stair and over an obstacle. These differences were accentuated during stepping under the simple reaction time instruction. These results speak against the hypothesis of a single motor program that would underlie postural preparation to stepping. They are more compatible with the reference configuration hypothesis of whole-body actions.

Patterns of morphological diversity among and within arcid bivalve species pairs separated by the Isthmus of Panama

2001 ◽  
Vol 75 (3) ◽  
pp. 590-606 ◽  
Author(s):  
Peter B. Marko ◽  
Jeremy B. C. Jackson
Keyword(s):  
Morphological Variation ◽  
Fossil Record ◽  
Eastern Pacific ◽  
Nominal Species ◽  
Western Atlantic ◽  
Isthmus Of Panama ◽  
Species Pairs ◽  
Recent Species ◽  
Discriminant Analyses ◽  
Collection Sites

Geminate species are morphologically similar sister-species found on either side of the Isthmus of Panama. The existence of all geminates in the tropical Eastern Pacific ocean and the Caribbean Sea is most often explained by vicariance: closure of the Central American Seaway 3.1 to 3.5 Ma simultaneously isolated populations of species with amphi-American distributions. In this paper, we test the potential of morphological measurements for discriminating between Recent geminate species pairs from three genera (Arca, Arcopsis, and Barbatia) in the bivalve family Arcidae and examine the prospects for distinguishing nominal species in the fossil record. Fourteen morphological variables were used to characterize shell shape and multivariate methods were used to discriminate between five Recent species pairs. Collection sites were also used as a priori groups for discrimination to describe patterns of intraspecific morphological variation and to evaluate differences among samples from different geographic regions.On average, 84 percent of specimens within geminate pairs are classified correctly following five separate discriminant analyses with nominal species as the grouping variable. Although all but one arcid species pair are discriminated with high statistical significance, some collection sites within species are highly morphologically distinct. Overall, a large proportion of specimens from each collection locality (79 percent on average) can be classified correctly to site although no single site possessed a multivariate centroid that was significantly different from all other conspecific centroids. The distinctiveness of some collection sites, however, raises the possibility that some nominal species may harbor cryptic species, indicating the need for wider geographic surveys of both molecular and morphological variation within geminate species pairs.The eigenvalue coefficients derived from the Recent samples of one geminate pair (Arca mutabilis and A. imbricata) were used to assess the potential for identifying arcid species in the fossil record. Discriminant analyses of fossil Arca indicate that the forms that characterize Recent A. mutabilis and A. imbricata are present in the fossil record as far back as the Late Early Miocene, in the Cantaure Formation of Venezuela. Because a deep water connection between the Eastern Pacific and Western Atlantic existed until the Middle Miocene, the morphological differences associated with Recent A. mutabilis and A. imbricata likely existed well before the rising Isthmus affected ocean circulation patterns in tropical America. Therefore, despite great overall morphological similarity, these putative geminate species likely have a time of divergence that is at least four times older than final seaway closure. The geographic distribution of fossils also suggests that morphological forms associated with each Recent species had amphi-American distributions both before and after isthmus formation but are now geographically restricted to either side of the isthmus in the Recent fauna.

scholarly journals Base-substitution mutation rate across the nuclear genome of Alpheus snapping shrimp and the timing of isolation by the Isthmus of Panama

2020 ◽  
Author(s):  
Katherine Silliman ◽  
Jane L. Indorf ◽  
Nancy Knowlton ◽  
William E. Browne ◽  
Carla Hurt
Keyword(s):  
Mutation Rate ◽  
Sequence Data ◽  
Nuclear Genome ◽  
Base Substitution ◽  
Snapping Shrimp ◽  
Isthmus Of Panama ◽  
Species Pairs ◽  
Genotype By Sequencing ◽  
Independent Calibration ◽  
Taxonomic Groups

AbstractThe formation of the Isthmus of Panama and final closure of the Central American Seaway (CAS) provides an independent calibration point for examining the rate of DNA substitutions. This vicariant event has been widely used to estimate the substitution rate across mitochondrial genomes and to date evolutionary events in other taxonomic groups. Nuclear sequence data is increasingly being used to complement mitochondrial datasets for phylogenetic and evolutionary investigations; these studies would benefit from information regarding the rate and pattern of DNA substitutions derived from the nuclear genome. To estimate this genomewide neutral mutation rate (μ), genotype-by-sequencing (GBS) datasets were generated for three transisthmian species pairs in Alpheus snapping shrimp. Using a Bayesian coalescent approach (G-PhoCS) applied to 44,960 GBS loci, we estimated μ to be 2.64E-9 substitutions/site/year, when calibrated with the closure of the CAS at 3 Ma. This estimate is remarkably similar to experimentally derived mutation rates in model arthropod systems, strengthening the argument for a recent closure of the CAS. To our knowledge this is the first use of transisthmian species pairs to calibrate the rate of molecular evolution from GBS data.

scholarly journals Late Toarcian marine gastropods from the Cleveland Basin, UK: systematics, palaeobiogeography and contribution to biotic recovery from the early Toarcian extinction event

2019 ◽  
Author(s):  
Mariel Ferrari ◽  
Crispin TS Little ◽  
Jed W Atkinson
Keyword(s):  
Mass Extinction ◽  
Taxonomic Composition ◽  
The Other ◽  
Gastropod Species ◽  
Marine Gastropods ◽  
Potential Explanation ◽  
Biotic Recovery ◽  
Extinction Event ◽  
Sandstone Formation ◽  
Mass Extinction Event

As part of a study to evaluate the recovery from the early Toarcian extinction event in the Cleveland Basin, 477 new gastropod specimens were collected from mid-late Toarcian rocks of the Ravenscar section, North Yorkshire, UK. The gastropods were preserved in two modes: 1) specimens preserved with recrystallized shells, mainly in the Whitby Mudstone Formation, but also some in the Blea Wyke Sandstone Formation; 2) specimens preserved as external moulds in mineralized patches of shells in the Yellow Sandstone Member. The fossil assemblage comprised fifteen species, of which three are new: Katosira? bicarinata sp. nov., Turritelloidea stepheni sp. nov. and Striactaenonina elegans sp. nov. Four species are described in open nomenclature, as Tricarilda? sp. Jurilda sp., Cylindrobullina sp. and Cossmannina sp. The other species have previously been described: Coelodiscus minutus (Schübler in Zieten), Procerithium quadrilineatum (Römer), Pseudokatosira undulata (Benz in von Zieten), Palaeorissoina aff. acuminata (Gründel), Pietteia unicarinata (Hudleston), Globularia cf. canina (Hudleston), Striactaeonina cf. richterorum Schulbert & Nützel, Striactaenonina aff. tenuistriata (Hudleston) and Sulcoactaeon sedgvici (Phillips). Most of these species are the earliest records of their respective genera and show palaeobiogeographical connections with contemporary gastropod associations from other regions of Europe and South America. The taxonomic composition of the late Toarcian Cleveland Basin gastropod assemblage differs substantially from the faunas of the late Pliensbachian and early Toarcian Tenuicostatum Zone, showing the strong effect of the early Toarcian mass extinction event on the marine gastropod communities in the basin. Only a few gastropod species are shared between the late Toarcian faunas and the much more diverse Aalenian gastropod faunas in the Cleveland Basin, suggesting there was a facies control on gastropod occurrences at that time. This is also a potential explanation for the taxonomic differences between the late Toarcian gastropod faunas in the Cleveland Basin and those in France, and Northern and Southern Germany.

scholarly journals Changes in the Gut Microbiome Community of nonhuman primate following radiation injury

2020 ◽  
Author(s):  
Raj Kalkeri ◽  
Kevin Walters ◽  
William Van Der Pol ◽  
Braden C. McFarland ◽  
Nathan Fisher ◽  
...  
Keyword(s):  
Radiation Exposure ◽  
Gut Microbiome ◽  
Radiation Injury ◽  
Lactobacillus Reuteri ◽  
Whole Body ◽  
High Dose ◽  
Microbiome Composition ◽  
Post Irradiation ◽  
High Doses ◽  
The Impact

Abstract Background Composition and maintenance of the microbiome is vital to gut homeostasis. However, there is limited knowledge regarding the impact of high doses of radiation, which can occur as a result of cancer radiation therapy, nuclear accidents or intentional release of a nuclear or radioactive weapon, on the composition of the gut microbiome. Therefore, we sought to analyze alterations to the gut microbiome of nonhuman primates (NHPs) exposed to high doses of radiation. Methods Fecal samples were collected from 19 NHPs (Chinese rhesus macaques, Macaca mulatta) one day prior and one and four days after exposure to 7.4 Gy cobalt-60 gamma-radiation (LD70 − 80/60). The 16S V4 rRNA sequences were extracted from each sample, followed by bioinformatics analysis using the QIIME platform. Results Alpha Diversity (Shannon Diversity Index), revealed no major difference between pre- and post-irradiation, whereas Beta diversity analysis showed significant differences in the microbiome after irradiation (day + 4) compared to baseline (pre-irradiation). The Firmicutes/Bacteriodetes ratio, a factor known to be associated with disruption of metabolic homeostasis, decreased from 1.2 to less than 1 post-radiation exposure. Actinobacillus, Bacteroides, Prevotella (Paraprevotellaceae family) and Veillonella genera were significantly increased by more than 2-fold and Acinetobacter and Aerococcus genus were decreased by more than 10-fold post-irradiation. Fifty-two percent (10/19) of animals exposed to radiation demonstrated diarrhea at day 4 post-irradiation. Comparison of microbiome composition of feces from animals with and without diarrhea at day 4 post-irradiation revealed an increase in Lactobacillus reuteri associated with diarrhea and a decrease of Lentisphaerae and Verrucomicrobioa phyla and Bacteroides in animals exhibiting diarrhea. Conclusion Our findings demonstrate that substantial alterations in the microbiome composition of NHPs occur following radiation injury and provide insight into early changes with high-dose, whole-body radiation exposure. Future studies will help identify microbiome biomarkers of radiation exposure and develop effective therapeutic intervention to mitigate the radiation injury.

scholarly journals Deletion of Trim28 in committed adipocytes promotes obesity but preserves glucose tolerance

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Simon T. Bond ◽  
Emily J. King ◽  
Darren C. Henstridge ◽  
Adrian Tran ◽  
Sarah C. Moody ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Energy Homeostasis ◽  
Whole Body ◽  
Epigenetic Mechanisms ◽  
Adipocyte Size ◽  
Tripartite Motif ◽  
Specific Manner ◽  
Bona Fide ◽  
Developmental Role ◽  
Body Energy

AbstractThe effective storage of lipids in white adipose tissue (WAT) critically impacts whole body energy homeostasis. Many genes have been implicated in WAT lipid metabolism, including tripartite motif containing 28 (Trim28), a gene proposed to primarily influence adiposity via epigenetic mechanisms in embryonic development. However, in the current study we demonstrate that mice with deletion of Trim28 specifically in committed adipocytes, also develop obesity similar to global Trim28 deletion models, highlighting a post-developmental role for Trim28. These effects were exacerbated in female mice, contributing to the growing notion that Trim28 is a sex-specific regulator of obesity. Mechanistically, this phenotype involves alterations in lipolysis and triglyceride metabolism, explained in part by loss of Klf14 expression, a gene previously demonstrated to modulate adipocyte size and body composition in a sex-specific manner. Thus, these findings provide evidence that Trim28 is a bona fide, sex specific regulator of post-developmental adiposity and WAT function.

Coupling between gamma irradiation, p53 induction and the apoptotic response depends upon cell type in vivo

1995 ◽  
Vol 108 (5) ◽  
pp. 1843-1848 ◽  
Author(s):  
C.A. Midgley ◽  
B. Owens ◽  
C.V. Briscoe ◽  
D.B. Thomas ◽  
D.P. Lane ◽  
...  
Keyword(s):  
P53 Protein ◽  
Whole Body ◽  
Protein Accumulation ◽  
Cell Type ◽  
Apoptotic Response ◽  
Adult Mice ◽  
Specific Manner ◽  
Massive Apoptosis

The accumulation of p53 protein following whole body irradiation of adult mice was studied using a new polyclonal antibody to mouse p53. While dramatic accumulation of the protein was apparent in splenocytes, thymocytes and osteocytes no p53 protein accumulation was detected in the hepatocytes of the irradiated mouse. Thus, the upstream initiating signals that control the induction of p53 are controlled in a tissue specific manner. While massive apoptosis accompanies p53 induction in thymocytes and splenocytes it is not seen in the osteocytes. Thus the downstream consequences of p53 induction are also tightly controlled. These results have profound significance for an understanding of the role of the p53 tumour suppression pathway in different tissues.

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